My suggestions are the following:
Remove dodge from prerequisites. This messes the stat spread too much. There's not a single passable Defender build left. Defenders don't benefit from having 13 dexterity in any way, not to mention gold dwarves even get a penalty on it. It's a heavy sacrifice for nothing.
Improve Defensive Stance with Dwarven Defender levels. Tanking requires AC in Arelith. Seeing as Defensive Stance cannot be toggled together with Improved Expertise, a scaling AC bonus to it would be ideal. This is the iconic ability of this class. Make it worthwhile!
The current bonuses from Defensive Stance are:
Considering Defenders don't lose AB, but cannot move in this stance, I think something similar would be a reasonable approach:+2 STR (Subject to +12 cap)
+4 CON (Subject to +12 cap. Very unreliable because toggling it off in low HP could result to death)
+2 saves (Good)
+4 dodge AC (You'd be much better off with Improved Expertise in most of the cases)
+4 dodge AC at level 1 (Currently)
+5 dodge AC at level 6
+6 dodge AC at level 12 (2 more AC!)
Feedback, criticism and more suggestions are very much welcome. Let's make this PrC playable, please. Thanks for your time.